I have a Coleman 3400-815. It no longer works in auto mode. I can manually switch it to "on" at the furnace, but it only blows cold air. I replaced the thermostat to see if that would help, but it still won't come on unless I use the furnace switch. I have a good multimeter, the wiring diagram, and plenty of automotive electrical experience, but don't have a clue about my furnace. Please help. Nicole
Make : ColemanModel : 3400-815
Please stand by while i draw up some info on your furnace. From your comments i gather that the heat is not working... but you are able to get the blower on. is this correct?
Can you do a check for me? Can you open your tstat exposing the wire terminals, put your tester on A/C volts and test between R and W. See if you have 24 to 28 volts.
Do this while i am gathering more info. please!
Nicole! your wonderful! so fast! Ok... i have been on line and have not located your electrical schemematic yet. I wanted to make sure you didnt blow a fuse or something.
now... can you disconnect the red wire and put it with the white wire? Try this and see if you get the heat to come on.
I held the wires together, it did not come on.
did you see some breakers on your electric furnace? if you do then turn them both off. snapping them real hard. Stand to the right or left and turn away snapping them one at a time real hard on. I know this sounds weird but this is how we electricians do just in case there is a flash. Now i was talking about breakers on the unit it self not the circuit breaker panel.
I can't find any breakers on the furnace.Would they be in the front under the panel? According to the wiring diagram I have the thermostat, fan switch, transformer, blower, fuse and disconnect assy., sequencers, limit switches, and heating elements. Hope this helps some.
Yes they must be fuses then and they are under the panel... now if you go in there be real careful... You need to check the fuses. to see if any are burnt open. This could be if you left the filter dirty to long or there is a fault in the heater elements. Can you do this?
The best and easiest way is to do it hot while checking with your meter... this way you dont have to pull any out unless they are burnt. just take your meter leads and put one on one end and one on the other end of the fuse where its made of metal. Now dont touch any of this stuff with your hands! its 240volts. Make sure you put your meter on the higher voltage scale. If you decide to check the fuses hot, see if you get a voltage when you test each one, top and bottom. if you get a zero or a few volts the fuse is good. if you get a 240volts the fuse is bad...understand?
Ok, that was a bit scary. All 4 fuses are good and tested around .008
You're doing great...So you have good voltage on tstat and fuses... i think what you have out is called the sequencers but i cant understand how both sets can be bad at the same time unless they went out over a period of time and you didnt notice.
Now i dont know how many heat strips you have but you have 4 fuses so you may have as many as 4 heat strips. can you tell me if you see a 60 amp on each fuse?
I just moved in a few months ago and the furnace never seemed blow as warm as I thought it should (if that helps at all).
I have (2) 60amp and (2) 30 amp fuses. From the wiring diagram, it appears I have 3 heating elements
from your fabulous help i believe you have 15 kw heat. now this means you more than likely have one single pole sequencer and 1 double pole sequencer... these must be out if nothing comes on when you turn the heat on at the thermostat... be sure the tstat has been switched to electric heat...check tstat manual for this.
now let me get a picture of the sequencers for you:
now this is what i think you have
but on the same plate like this:
is this correct or is it like the one to the left?
The images are vertical so I'm not sure what you mean by the one on the left. It looks like I have 2 on the same plate, one single and one double. Are there stores that might sell these or do I need to order replacements online? Anything I need to know about replacing them?
look and see if yours match any of the pictures. Yes you can buy on line or at a local store... what city are you in?
The pics of each sequencer matches except my shorter one has 4 prongs on the bottom (2 on each side) and 2 prongs on top (1 on each side) so missing 1 top prong. The taller seq. matches except the top has 3 prongs (1 on one side and 2 on other) rather than 4 in the pic. I hope this makes sense.
I am in Monroe, WA
yes it does... now i am positive you have 15 kw heat... it is either going to be the sequencer or the fan switch... we dont want you to buy parts you dont need so we have to look for the problem... are you willing to keep checking?
Sounds good. What should I check next?
on the double stack sequencer, you must check the lower wire connections with your volt meter to see if it is getting a signal of 24 to 29 volts. Do you have a black wire on one side and a white wire on the other ?(on the bottom stack of the double sequencer)
be careful it might be a tight squeeze in there!
I do have a black wire and white wire. Do I put one lead on the blk and one on the wht?
yes! youre good.
But make sure the tstat is calling for heat and the temperature is up!
look for 24 to 29 volts. the upper stacks have 240 volts so be careful!!!
Looks good, 25.9
now, put your meter leads on the top two wire connections and tell me if after 60 seconds if you have a reading of 0 or 240volts?
now do this with a call for heat and all.
I'm not sure which top two wires you mean. On the same seq. I have 2 wires on the next level (2 reds) and 3 wires on the top level (2 yellow 1 grey).
Sorry about that... on the top level or stack what ever you want to call it... the voltage goes across horizontally on these sequencers... the bottom is 24 v and the next two levels or stacks are 240 volts, lets check the top level put one lead on the yellow with the other lead on the other yellow across from the first. then do the same with the red wires...let me know what the voltage is for each...remember to wait 60 seconds or so for the sequencer to switch (if it was really a working unit).
No problem, you have been great. I got 238.5 for both and remained right about the same for the entire 60 sec.
Ok this is wonderful!! why because you just told me that the bottom of the sequencers have 24 volts and the top you are reading 230 something volts, which is the same as saying that the sequencer is not operational! if it was working you would see a zero or there abouts on the two red wires and a zero on the two yellow wires. Now i believe the other sequencer is bad also so just replace em both. You can find your parts on line at
Americanhvacparts.com or your nearest parts house. just look up air conditioning at whitepages.com for your city or zip. call em before you go to make sure they will sell it to you.
22 years Licensed Contractor State of Texas
Thank you so much for all your help! You have been fantastic. I couldn't possibly afford to have a repair person come out, so I really appreciate it. Now my kids and I can finally get some heat. Thank you so much.
That is so wonderful that you did all that. I am really proud of you. Now be sure when you change out the parts you turn the breaker off and tape it off with duct tape... i dont want anyone to turn it on while you are working on it. (kids) Take and make a drawing of the wires and where they go. so you can put them back on the right spot. Later if you get mixed up just give us another question and request me.
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